In recent years the manufacturers of color photographic photosensitive materials have made progress in increasing the photographic speed of photosensitive materials and increasing picture quality in response to the needs of the user. In this connection, increased image quality has involved the improvement of graininess, the improvement of sharpness and the improvement of color reproduction. These factors are very important in determining the performance of a photosensitive material, and it is clear that improvements in these factors will have to continue in the future.
In connection with color reproduction from among these factors, attention has been focused in recent years on improving the hue of the magenta color by using pyrazoloazole based magenta couplers in place of the 5-pyrazolone type couplers which had been used in the past.
The dyes which are formed by the reaction between these couplers and oxidation products of color developing agents have little of the harmful side absorbance which affects color reproduction and so the color reproduction range can be widened. These couplers have been disclosed, for example, in U.S. Pat. Nos. 3,725,067 and 4,621,046 and other publications. (The term "JP-A" as used herein signifies an "unexamined published Japanese patent application".)
On the other hand, the inclusion of formaldehyde in the final bath in the development processing of camera color materials (color negative and color reversal materials) is well known for improving the fastness of the magenta image.
Much research has already been done in connection with the role of formaldehyde and, for example, the fact that a pyrazolone coupler reacts with azomethine dyes and provokes fading of the dyes has been disclosed by P. W. Vittum and F. C. Duennebier in J. Am. Chem. Soc., 72, 1536 (1950). On the other hand, the addition of formaldehyde to a stabilizing bath to prevent unreacted couplers from reacting with dyes, which in turn prevents fading, has been disclosed by R. W. G. Hunt in The Reproduction of Color, second edition, J. Wiley and Sons, Inc., New York, p.306 (1967). Furthermore, similar disclosures have also been made in The Journal of Photographic Science, 36, 64 (1988). Formaldehyde thus plays a major part in the fastness of the image, but it causes problems in connection with environmental protection and there is a strong demand for its removal from photographic processing liquids.
As an example, it is disclosed in JP-A-60-98435 that these is no loss of colored image fastness when a two-equivalent pyrazolone coupler is used even when essentially no formaldehyde is included. Moreover, it is disclosed in JP-A-62-54261 that there is no loss of colored image fastness even when the formaldehyde is omitted from the stabilizing bath when a two-equivalent type pyrazoloazole type coupler is used. However, in the former case there is no improvement in color reproduction, and in the latter case the worsening of graininess is a serious problem.
Moreover, the fact that no formaldehyde is included in the Ektaprint 3 chemicals which are the processing baths for the new magenta couplers introduced by the Kodak Co. in Ektacolor 30RC has been disclosed in J. Imag. Tech., 11, 93 (1985). The magenta couplers used here are the four-equivalent anilino type magenta couplers which have so-called anilino substituent groups as disclosed, for example, in U.S. Pat. No. 3,127,269.
It is possible to omit the formaldehyde from the stabilizing bath when these couplers are used. However, there is inadequate improvement in color reproduction when the above mentioned couplers are used in camera materials and there is a particular and serious problem in that reds are reproduced as scarlet colors.
These four-equivalent anilino type magenta couplers give rise to problems with color reproduction when used as they are, being at a shorter wavelength than the magenta couplers which have acylamino groups as substituent groups which have been used conventionally in camera materials, and the reproduction of reds is adversely affected. Moreover, saturation is greatly improved when two-equivalent pyrazoloazole types are used, but this has the disadvantage of greatly worsening the graininess.
Moreover, when processed in a color developer of pH 11 or above there is a pronounced increase in color mixing between layers and this is very noticeable when two-equivalent pyrazoloazole types are used in camera color reversal photographic photosensitive materials.